As a fuel injection valve that injects and supplies fuel to each cylinder of an internal combustion engine mounted on a vehicle of the like, for example, an electromagnetically driven type has been known. In such a type of fuel injection valve, fuel injection period and fuel injection amount are controlled by controlling energization period and energization timing of a solenoidal coil embedded in a fuel injection valve body to drive a valve body in a valve opening direction.
Furthermore, in order to meet a requirement of the micro injection, a partial lift injection in which a lift amount of a valve body of a fuel injection valve dose not reach a full lift position has been studied recently, and for example, a technique of Patent Literature 1 has been known as a technique for solving variation of injection amount in the partial lift injection. In the technique described in Patent Literature 1, a terminal voltage of a solenoid is detected for each of fuel injection valves of cylinders. Then, in a case where the valve body is closed from a valve opened state, induced electromotive force is changed due to change of acceleration of a mover when the mover is separated from the valve body after being in contact with a valve seat. In this case, the timing at which a second order differential value of the terminal voltage of the solenoid is determined as a valve closing timing of the valve body to appreciate injection amount variation on the basis of the valve closing timing.
However, as described above, in a case where the induced electromotive force is changed when the valve body is closed from a valve opened state, when the valve closing timing is determined on the basis of the second order differential value of the terminal voltage of the solenoid, to correctly determine the valve opening timing probably fails except the area in which the valve body lift amount is large to some extent, in other words, except the area in which an injection pulse width is long to some extent. In this case, micro injection is performed in the partial lift injection, but determination of the valve closing timing of the valve body in the micro injection is difficult, so that probably there is room for technical improvement.